The following is an example of running rb_calltime.d and tracing the elapsed
times for functions.
We run rb_calltime.d while running the program Code/Ruby/func_abc.rb. We can
see that there are four sections in the DTrace output
# rb_calltime.d
Tracing... Hit Ctrl-C to end.
^C
Count,
FILE TYPE NAME COUNT
. obj-new NoMemoryError 1
. obj-new SystemStackError 1
. obj-new ThreadGroup 1
. obj-new fatal 1
func_abc.rb func Object::func_a 1
func_abc.rb func Object::func_b 1
func_abc.rb func Object::func_c 1
. obj-new Object 3
func_abc.rb func IO::write 3
func_abc.rb func Module::method_added 3
func_abc.rb func Object::print 3
func_abc.rb func Object::sleep 3
- total - 15
Elapsed times (us),
FILE TYPE NAME TOTAL
. obj-new SystemStackError 3
. obj-new NoMemoryError 3
. obj-new fatal 11
. obj-new ThreadGroup 13
. obj-new Object 26
Exclusive function elapsed times (us),
FILE TYPE NAME TOTAL
func_abc.rb func Module::method_added 9
func_abc.rb func Object::print 92
func_abc.rb func IO::write 185
func_abc.rb func Object::func_c 344
func_abc.rb func Object::func_a 379
func_abc.rb func Object::func_b 383
func_abc.rb func Object::sleep 3020597
- total - 3021992
Inclusive function elapsed times (us),
FILE TYPE NAME TOTAL
func_abc.rb func Module::method_added 9
func_abc.rb func IO::write 185
func_abc.rb func Object::print 277
func_abc.rb func Object::func_c 1009829
func_abc.rb func Object::func_b 2019781
func_abc.rb func Object::sleep 3020597
func_abc.rb func Object::func_a 3021983
The first section, Count, shows us how many times each function associated
with func_abc.rb was called. It also shows other functions called by the Ruby
engine.
The second section, elapsed times, shows how long each action that was not
calling a function took.
The third section, exclusive function elapsed times, shows us how many
microseconds the program spends in each function. This does not include the
time spent in any sub-functions called by that particular function. The last
line gives us the total time in microseconds.
The fourth section, inclusive function elapsed times, are the absolute time
from when the function began to when it completed - which includes off-CPU time
due to other system events such as I/O, scheduling, interrupts, etc. In
particular, for this case it has included the time waiting for the sleep
commands.
Elapsed times are useful for identifying where latencies are.
See Notes/ALLelapsed_notes.txt for more details. Also see
Notes/ALLexclusive_notes.txt and Notes/ALLinclusive_notes.txt for a
detailed explanation of exclusive vs inclusive function time.